Impact wrench



May 4, 1954 A. coFFMAN ErAL 2,677,52

IMPACT WRENCH Filed May 31, 1949 Patented May 4, 1954 IMPACT WRENCH Alvin Coffman,

Indiana Harbor, Ind., and John Marshall, Chicago, Ill., assignors to Inland Steel Company, a

corporation of Delaware Application May 31, 1949, Serial No. 96,244

1 Claim.

rhis invention relates to impact wrenches, and in particular it relates to themeans by which the interchangeable socket heads are detachably secured in the chuck.

Impact wrenches, and inparticular the large ones which are used for the assembly of heavy industrial equipment in steel mills and the like, present a peculiar problem, because no conventional chuck is suitable for retaining a socket head weighing from three to iifteen or twenty pounds, under the combined turning thrust and hammering force of a large impact wrench.

The spring pressed balls which are used in small chucks for holding light drill points or socket heads cannot be made with heavy enough springs to keep a three pound socket head from falling out of the chuck if the wrench is turned with its head down. Since the wrenches are often used in high level assembly operations in industrial plants, the possibility of the heavy socket head falling out of the chuck presents a tremendous hazard.

The usual commercial chuck andv socket head are provided with registering apertures to recelve a taper pin or Cotter pin; but the combina tion of torque and impact causes a great deal of breakage of pins, permitting the heavy socket head to fall out of the chuck.

The operators using the big impact wrenches have tried such expedients as driving a heavy piece of drill rod through the apertures, to give a stronger pin. These also break; and since pro .iecting ends must be left on the rod they are unbalanced and may rly out when the wrench is rotating at high speed.

In our improved chuck and socket head, the drive shaft for the wrench has adjacent its outer end a flange upon which the bottom of the socket head shaft rests, and this flange is provided With an integral skirt to form a well for the shaft of the socket head. The driving connection is by means of a square spindle in the Well which engages a square nipple in the base of the socket head. The skirt is provided with a pair of opposed apertures through which ball bearings project to make engagement with an annular groove in the base of the socket head. An internally shouldered ball retaining cup surrounds the skirt. and is slidably mounted on the drive shaft. When the ball retaining cup is in its normal, or forward position, the internal shoulder abuts against the balls and holds them in engagement with the annular groove on the socket head shaft. A spring pressed pin extends from the ange through a hole in the Wall of the ball retaining cup to normally retain the cup in its forward position. The spring pressed pin may be depressed to release the cup for movement to its release position, at which position the balls may roll outwardly a suflicient distance to disengage from the annular groove in the socket head shaft. To again lock the socket head in the chuck, it is only necessary to slide the ball retaining cup to its normal forward position where its shoulder again locks the balls in engagement with the annular groove of the socket head shaft. The spring pressed pin automatically re-enters the hole in the wall of the ball retaining cup when it is in registry therewith, to hold the retaining cup in its forward position.

It is thus seen that the socket head may be detached from the chuck only-by manually depressing the spring pressed pin, and that in operation of the wrench there are no forces tending to disengage the pin or move the ball retaining cup to its release position.

Fig. l is a side elevation of an impact wrench with the improved chuck and associated socket head partially in cross-section; Fig. 2 is a central vertical section through the chuck and socket head With the latter locked in the chuck; Fig. 3 is a fragmentary sectional View similar to Fig. 2, but with the chuck in its disengaging position to permit removal of the socket head; Fig. 4 is a section, taken as indicated at @-4 of Fig. 2; and Fig. 5 is a section, taken as indicated at 5 5 of Fig. 2.

Referring to the drawings in greater detail, an impact wrench indicated generally at l is provided with a removable drive shaft H, having a anged inner end I2 to make driving connection with suitable recesses in the driving member of the wrench. Impact wrenches of this type, and having this type of drive linkage, are very well known. The invention relates to the means by which the chuck, indicated generally at H3, and the socket head, indicated generally at i4, are secured together.

As seen in Fig. 5, the outer end of the drive shaft H has its opposite sides milled off to form flats i5, the inner ends of which form shoulders I6. As seen in Fig. 4, at its extreme end portion, the shaft is cut to form a square shank or driving lue,r I1.

As best seen in Figs. 2 and 5, a flange I8 surrounds the drive shaft at the base of the driving lug I1, and is bored to receive set screws Illa, by which it is secured to the drive shaft l I. The cup A25 is apertured to permit installation of the set screws, which are of the headless, self-locking thread type, and preferably the apertures in the cup are then plugged with at headless screws 85. Flange I8 has an annular upright wall i9 to form a well 20 on the drive shaft of appropriate diameter to receive the base portion 2l ofthe socket head Ill. A square bore in the base` 2l embraces and makes driving connection With'the driving lug I1.

The upright side wall I9 of the well is provided with a pair of opposed apertures 22 in each of which is mounted a retaining member 23. In the preferred embodiment shown, the apertures 22 have annular anges 22a at the inner surface of the side wall I9, and the retaining members 23 are steel balls which are free to roll within the apertures 22 and to project into the Well through the restricted openings afforded by the flanges 22a, where they may engage an annular groove 2e in the base of the socket head I4.

A cup 25 embraces the Well to form rigid means for releasably locking the steel balls 23 in their latching position projecting into the annular groove 24 in the base of the socket head lil. The cup 2.5 is slidably mounted on the flats I5 of the drive shaft, and the shoulders l limit its rearward motion. The inner surface of the side Wall of the cup 25 has a beveled shoulder 2E to provide a short, inclined portion connecting the lower small diameter part 21 of the cup and the upper large diameter part 28 thereof.

As best seen in Figs. 2 and 3, the lower part 2l makes a snug, sliding fit with the side wall i9 of the well, while the upper part 28 of the cup provides substantial clearance about the exterior of the well. The cup is slidable between a normal forward position, shown in Fig. 2, in which the lower part 2 of the side wall abuts against the steel balls 23 to hold them in their latching position; and the retracted position shown in Fig. 3, in which the enlarged forward part 28 of the cup is in registry with the apertures22 and balls 23 so as to leave clearance for the balls to move to a retracted position out of engagement with the annular groove 24 of the socket head.

As best seen in Figs. 1 and 5, the flange I8 which forms the base of the well is bored to receive a spring pressed pin 29 which projects outwardly into an aperture 30 in the side wall of thecup 25 so as to normally retain the cup 25 in its forward position in which the balls k243 are positively, retained in engagement with the groove `24. When the outer end of the spring pressed pin 29 is pushed in a sufficient distance to Yclear the inner surface of the side wall of the cup, the cup is then free to be moved to its retracted position to release the balls 23 for movement to their re.- tracted positions.

The foregoing detailed description is given for clearness of understanding only, and no unnecessary limitations should be understood therefrom, as modifications will be obvious to those skilled in the art.

We claim:

In an impact wrench a socket head having a base provided with a central, non-circular bottom aperture to receive a driving lug and having a peripheral groove inl its side wall: a driving shaft having at its outer enda non-circular axial driving lug; an annular ring member encircling the driving lug and being secured thereto by a plurality of screws extending through the annular ring member and into the driving lug, said annularring member having an axially extending flange adjacent its outer periphery spaced from the driving lug to provide a well for the base of the sockethead, and having a radially extending hole through the flange; a ball member in said hole engaging the recess in the base of the socket head when in latching position; a rigid cup member slidably mounted on the ydriving shaft, said cup member having ,a plurality of threaded holes therethrough inalignmentr with the screws when in latched position and being adapted to receive plug screw means and` anaxially extending annular wall portion fitting over the ball vmember when in .latohns position to lock the socket head with the drive shaft against axial movement and being movable between `a position fitting over the ball member and a release position.; and means for locking the cup member against axial or rotational movement relative to theball member when in latched position including a shouldered pin having a body portion and a head portion r smaller in cross-sectional area than the body portion, said pin being movable radially within a radially extending opening in the annular ring member, and a spring in ,saidradial opening urging said pin outwardly of said radial opening and vurging thehead portion of the pin into a hole in the axially extending annular wall portion of the rigid cup, said hole in the wall portion of the rigid vcup being at least as large as the head portion of the pin and smaller than the body portion and being nostionedto receive the head portion of the pin when the wall portion of the rigid cup fits over the ball member.

Referencesy Cited in the filel of this patent UNITED STATES PATENTS Number Name Date 389,335 Spear Sept. 11, 1888 751,345 SaundersA Feb. 2, 1904 1,346,341 Schinkez July 13, 1920 1,636,421 Knott July 19, 1927 1,896,645 Pfauser Feb. 7, 1933 2,290,215 Stenberg July 21, 1942 2,395,534 Cook Feb. 26, 1946 2,474,360 Jimerson June 28, 1949 

